This invention relates generally to plasma enhanced chemical vapor deposition reactors, and to plasma enhanced chemical vapor deposition processes.
RF plasma enhanced chemical vapor deposition reactors include a deposition chamber comprising an electrically conductive RF powered showerhead support electrode (in some devices, referred to as a gas box) and an electrically conductive gas distributing showerhead mounted thereto. RF power is conducted therebetween by the inherent electrically conductive nature of the materials from which such components are fabricated. The showerhead support electrode and gas distributing showerhead are typically bolted to one another. Gas feed to the showerhead is typically provided through the showerhead support electrode ultimately to the back of the showerhead. The showerhead support electrode and the showerhead are typically made of dissimilar materials. For example, a gas distributing showerhead might principally or entirely comprise nickel, whereas the showerhead support electrode might principally or entirely comprise aluminum. Good RF electrical contact between these two components is highly desirable to achieve good and consistent deposition when processing a series of wafers within the chamber.
During deposition, the showerhead and support electrode might be at different temperatures. Further, even if at the same elevated temperature, their different materials will typically have different thermal coefficients of expansion. Accordingly, the showerhead support electrode and the showerhead may warp or separate slightly from one another, resulting in degradation of the electrical connection therebetween. This can adversely bias the RF coupling therebetween and deteriorate the process performance of the deposition within the chamber.
It was discovered that after cleaning and reassembly of a plasma enhanced chemical vapor deposition reactor, such as described above, as many as 100 or more wafers will be processed within the chamber before repeatable and predictable depositions desirably occur within the chamber. It is theorized that the processing of such a large number of wafers where some separation between the showerhead and the showerhead support has occurred eventually results in plasma deposition of electrically conductive material within some or all of the space separating the showerhead and showerhead electrode due to differential expansion. This thereby results in a good, steady state RF electrical connection between the support and the showerhead. However, ultimately the reactor is disassembled for cleaning or other purposes, thereby resulting in poor electrical contact and deposition for a large number of wafers upon subsequent initial processing with the reactor. Further, the initial wafers may not have consistent and uniform deposition within the group, effectively causing a xe2x80x9cbreak-in effectxe2x80x9d.
It would be desirable to overcome or improve upon the problems identified above. Although the invention was motivated primarily from this perspective, the artisan will appreciate applicability of the invention to plasma enhanced chemical vapor deposition processes and reactors independent of identification of or overcoming the above-identified problem, with the invention only being limited by the accompanying claims appropriately interpreted in accordance with the Doctrine of Equivalents.
The invention comprises a plasma enhanced chemical vapor deposition reactor, and a plasma enhanced chemical vapor deposition process. In one implementation, a plasma enhanced chemical vapor deposition reactor includes a deposition chamber comprising an electrically conductive RF powered showerhead support electrode. An electrically conductive gas distributing showerhead is mounted to the RF powered showerhead support electrode. A preformed electrically conductive gasket is interposed between the RF powered showerhead support electrode and the gas distributing showerhead.
In one implementation, a plasma enhanced chemical vapor deposition process sequentially includes, a) in a first plurality of discrete depositions, plasma enhanced chemical vapor depositing material upon a plurality of semiconductor substrates within a chamber of a plasma enhanced chemical vapor deposition reactor; b) disassembling the reactor at least by separating an electrically conductive RF powered showerhead support electrode of the reactor and an electrically conductive gas distributing showerhead of the reactor from one another; c) sandwiching an electrically conductive material between the electrically conductive RF powered showerhead support electrode and the electrically conductive gas distributing showerhead during a reassembly of the reactor at least including connecting the electrically conductive. RF powered showerhead support electrode and an electrically conductive gas distributing showerhead together; and d) in a second plurality of discrete depositions, plasma enhanced chemical vapor depositing material upon a plurality of semiconductor substrates within the chamber of the plasma enhanced chemical vapor deposition reactor.